Phenylated imide-quinoxaline copolymers

ABSTRACT

PHENYLATED IMIDE-QUINOXALINE COPOLYMERS CONSISTING ESSENTIALLY OF UNITS OF THE FORMULA   -((2-PHENYL-3,6-QUINOXALINYLENE)-X-(2-PHENYL-6,3-   HEXAHYDROBENZO(1,2-C:4,5-C&#39;&#39;)DIPYRROL-2,6-YLENE)-R)--   QUINOXALINYLENE)-R-(1,3,5,7-TETRA(O=)-1,2,3,5,6,7-   WHEREIN X IS A DIRECT BOND,   -O-, -CO-, -S-, -SO-, AND -SO2-   AND R IS M OR P-PHENYLENE WHICH ARE USEFUL AS COATINGS FOR FIBERS, GRAPHITE PRECURSORS, FILMS AND LAMINATING MATERIALS ARE PREPARED BY CONTACTING   1,2-DI(H2N-),4-((3,4-DI(H2N-)PHENYL)-X-)BENZENE   WITH   2,6-BIS(4-(PHENYL-CO-CO-)PHENYL),1,3,5,7-TETRA(O=)-   1,2,3,5,6,7-HEXAHYDROBENZO(1,2-C:4,5-C&#39;&#39;)DIPYRROLE OR   2,6-BIS(3-(PHENYL-CO-CO-)PHENYL),1,3,5,7-TETRA(O=)-   1,2,3,5,6,7-HEXAHYDROBENZO(1,2-C:4,5-C&#39;&#39;)DIPYRROLE

United States Patent Olfice 3,642,700 PHENYLATED [MIDE-QUINOXALINE COPOLYMERS Joseph M. Angl, Sterling Park, Va., assignor to the United States of America as represented-by the Secretary of 5 the Navy No Drawing. Filed Sept. 24, 1970, Ser. No. 75,248

Int. Cl. 008g /00, 33/02 US. Cl. 260- 6 Claims ABSTRACT OF THE DISCLOSURE Phenylated imide-quinoxaline copolymers consisting essentially of units of the formula wherein X is a direct bond,

0, -p-, s, so and so.

and R is m or p-phenylene which are useful as coatings for fibers, graphite precursors, films and laminating materials are prepared by contacting (ill M; /Q

. a l 3' e BACKGROUNDOF THE INVENTION This invention relates generally 'to polymers and more particularly to phenylated imide-quinoxaline copolymers and tov ,a method of preparation thereof.

3,642,700 Patented Feb. 15, 1972 Method of Preparation Thereof by Wolfgang J. Wrasid- 4 lo. Such polymers are known to have good oxidativethermal stability. Additionally some of these polymers, even those with a relatively high molecular weight, are very soluble in common organic solvents. Since these polymers can be used as coatings it ishighly desirable that they be easily removed by contacting with common organic solvents so that it is possible to inspect or repair materials which have been coated with them. Fur- 10 thermore, polymer coatings of the prior art often require a heat cure before they can be used thereby creating an additional step in using them effectively. A continuing search goes on for polymers which do not require a heat cure, which can be used as coatings and which 1 have good oxidative-thermal stability as well as good 30 solubility in common organic solvents.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide phenylated imide-quinoxaline copolymers.

35 Another object of this present invention is to provide phenylated imide-quinoxaline copolymers which have excellent oxidative-thermal stability.

A further object of this invention is to provide phenylated imide-quinoxaline copolymers which are readily 49 soluble in common organic solvents.

A still further object of the instant invention is to provide phenylated imide-quinoxaline copolymers which can be used as high temperature protective coatings, for fibers, graphite precursors, films and laminating materials.

A still further object of this invention is to provide a process for the preparation of phenylated imide-quin- Phenylated polyquinoxalines are known and have been Oxaline. p y

disclosed in copending application Ser. No. 876,572, filed Nov, 13, 1969 entitled Phenylated Polyquinoxalmes and.

Yet another object of the present invention is to provide a phenylated imide-quinoxaline copolymer which requires no heat cure before use because of irnide ring formation prior to polymerization.

A further object of this invention is to provide phenylated imide-quinoxaline copolymers which are prepared from relatively inexpensive materials.

These and other objects of this invention are accomplished by providing copolymers consisting essentially of units of the formula wherein X is selected from the group consisting of a direct bond,

and R is selected from the group consisting of M and p-phenylene which are prepared by contacting DESCRIPTION OF THE PREFERRED EMBODIMENT The phenylated imide-quinoxaline copolymers of this invention are prepared by reacting compounds of Formula II with compounds of Formula III when R is to be p-phenylene and with compounds of Formula IV when R is to be m-phenylene. The reaction sequence that is used to prepare compounds of Formula III is depicted as follows:

0 (VI) g S002 A620 HgN- O O (VII)C HCl i AcNH- O 0 (VIII) When compounds of Formula IV are desired the reaction sequence is identical except that is the initial starting material. The first step in the sequence is the reduction of the nitro group to the amino group by any of the conventional reduction techniques such as, for example, treatment with iron in acid solution to obtain V. The amino compound obtained is then acylated by reaction with acetic anhydride in the con ventional manner to obtain VI. Once acylated the compound is treated with selenium dioxide to oxidize the methylene group to a carbonyl to obtain VII. To form the amino analogue VIII, VII is treated with an acid. VIII is then converted to III by reaction with pyrornellitic dianhydride.

The polymer is prepared by reacting in a solvent, such as m-cresol, the tetraamine of Formula II with the com pounds of Formula III or IV. This reaction may be conducted entirely at room temperature or at somewhat elevated temperatures. It is desirable, though not necessary, to raise the temperature to above 100 C. 'for a few minutes at the end of the reaction in order to drive out the water that has formed during the reaction.

The general nature of the invention having been set forth, the following examples are presented as specific illustrations thereof. It will be understood that the invention is not limited to these specific examples but is susceptible to various modifications that will be recognized by one of ordinary skill in the art.

EXAMPLE 1 4'-aminodeoxybenzoin A mixture of 64.0 g. of 4'-nitrodeoxybenzoin, 40.0 g. of iron powder, 3.5 ml. of concentrated hydrochloric acid, 500 ml. of ethanol, and 250 ml. of water was refluxed for one hour. The hot solution was filtered and the filtrate poured into 1.5 liters of water, giving a slightly yellow precipitate, M.P. 7 C.

(III

3 EXAMPLE 2 4'-acetamidodeoxybenzoin Amixture of 20.0 g. of 4-aminodeoxybenzoin, 50 ml. of glacial acetic acid and 50 ml. of acetic anhydride was heated at reflux for tiwo hours and then poured into one liter of water, giving a white solid which was recrystallized from a mixture of ethanol-water (1:1), M.P. 158- 160 C. i

6 and this was filtered and washed with acetone; M.P. 365- 7 C. The solid can be recrystallized from m-cresol. No change in the IR spectra was obsenved after refluxing the compound for three hours in rn-cresol.

EXAMPLE 6 TABLE I.SYNTHESIS OF POLYMERS Polymer of Formula I wherein X and R are- Tetramine Concentration in X R (moles) Glyoxal m-cresol Pot temperature and reaction time 1...... Direct bond... p-Phenylene.. I 001 .001 percent, after 16 16 hours at room temp. then diluted to 3 percent and heated 15 hours at room min. at reflux. temp. diluted to 3 percent. 2 O do 3 .001 .001 5 percent 1 hour at 120 0., then 20 min. reflux.

O ..do........ .001 .001 4.3 percent... min. at room temp., then 00 min. 80 0, plus 1 hour 110 0., plus g 10 min. reflux. 4 SO 2 ..do.. 001 001 5 percent 2 hours at 120 C., then 20 min. at reflux.

1 N,N -bls (4-benzilyDpyromellitimide. 3,3 -diaminobenzidine. 3 4,4 ,3,3 -tetraaminodiphenylether. 4,4 ,3,3 -tetreaminobenzophenone. 6 4,4 ,3,3 -tetraaminodiphenylsulfone.

EXAMPLE 3 Table II lists some of the properties of the polymers 4-acetamidobenzil prepared Table A mixture of 18.0 g. of 4-acetamidodeoxybenzoin, 8.5 g. of selenium dioxide, and 200 ml. of glacial acetic acid was heated at reflux for two hours. The mixture was then poured into one liter of water. The yield of 4-acetamidobenzil monohydrate was 20 g., M.P. 105-8 C. After two recrystallizations from benzene the solid was dehydrated, M.P. 136-8 C.

EXAMPLE 4 4-aminobenzil ea ce A mixture of 15.0 g. of 4-acetamidobenzil and 150 ml. of concentrated hydrochloric acid was refluxed for four hours. The solid was filtered and made basic with sodium hydroxide to obtain the free base. The precipitated solid was recrystallized from ethanol-water (1:1) to give 12.1 g. of a pale yellow solid, M.P. 127-9" C.

EXAMPLE 5 N,N-bis (4-benzil)pyromellitimide A mixture of 5.8 g. of 4-aminobenzil, 2.81 g. of pyromellitic anhydride, and ml. of dimethylacetamide was stirred at room temperature for 3.5 hours while nitrogen was slowly passed through the reaction flask. Then 8 ml. of acetic anhydride and 2 ml. of pyridine was added. The

TABLE II.-PROPERTIES Polymer decomposition Inherent viscosity dl./g.: temperature C. (1) 1.80 550 aoilieiiermined in 98% sulfuric acid (0.5 g. in ml., at

Determined in m-cresol (0.5 g. in 100 ml., at 30 0.). Obtained from lGA data in vacuum at a heating rate of 5 0. per minute.

' r u L F E l) ll phenol, hexafluoroacetone, hexafiuoroisopropanol and are moderately soluble in tetrachloroethane.

What is claimed as new and desired to be secured by Letter Patent is:

1. Phenylated imide-quinoxaline copolymer consisting solution was refluxed for 8 hours. A tan solid precipitated i5 essentially of repeating units of the formula wherein X is selected from the group consisting of a direct bond,

0, -o-, s, so and so,

and a direct bond.

3. A phenylated imide-quinoxaline copolymer according to claim 2 where X is 0.

4. A phenylated imide-quinoxaline copolymer according to claim 2 where X is 5. A phenylated imide-quinoxaline copolymer according to claim 2 where X is S0 6. A phenylated imide-qninoxaline copolymer according to claim 2 where X is a direct bond.

References Cited FOREIGN PATENTS 1,388,650 1/1965 France 26065 OTHER REFERENCES Stille et al.: Polyquinoxalines, Polymer Letters, Journal of Polymer Science, vol. 2, pp. 209-211 (1964).

HAROLD D. ANDERSON, Primary Examiner L. L. LEE, Assistant Examiner US. Cl. X.R.

117--161 H; 260-328 N, 33.4 P, 3.8 R, 63 N, 65, 326 c, 558 R, 570 AB 

